Growing a Revolution, page 21
Donnelly began surprising crowds at cooking demonstrations by firing up his stoves for hours at a time—sometimes indoors—with no visible smoke. An independent emissions laboratory tested the stove and determined that it produced hardly any carbon monoxide. His clean-burning stove also produced high-quality charcoal.
A number of factors affect the quality of biochar, the combustion temperature and the quality of the starting organic matter chief among them. Lower temperatures produce more biochar. Higher temperatures produce a biochar with higher pH and higher nutrient availability (cation exchange capacity). But burn too hot and the porosity starts to collapse. The optimum temperature for making biochar is about 500°C (900°F), and Donnelly’s stoves hit that temperature and can char pretty much anything organic. He once showed me a whole charred black rose that looked like something out of a Tim Burton movie. But crop residue is the most likely input material for small-scale farmers in the developing world to turn into biochar. With a biochar cookstove they can use their crop wastes for cooking fuel and return the char to their soil.
Biochar can persist in the ground for centuries to millennia. That’s why archeologists date ancient sites by radiocarbon-dating charcoal. Yet how can biochar influence soil fertility if charcoal is so inert that it can last for thousands of years? It comes down to its high porosity, which increases the soil’s water holding and cation-exchange capacities, and its ability to increase soil pH, which reduces soil acidity to levels that favor beneficial microbial life. It also provides pore space and habitat for microbes that break down and recycle organic matter.
A number of studies demonstrate that biochar boosts both microbial activity and crop yields. In small test plots that mirror such studies, Donnelly saw a 30 percent increase in crop yields on poor soil and no increase from adding biochar to already fertile soils. Field trials in carbon-poor Amazonian soils have shown charcoal additions can more than double crop yields. And a study in French Guiana found that a combination of manioc peel and charcoal provided a bigger boost to both crop yields and earthworm activity than either soil amendment did alone. However, some studies have reported that applying biochar to already fertile soil can actually decrease yields.
At the crest of the mountains, we passed a big wind farm where hundred-foot-tall, triple-blade turbines spun in the Pacific winds spilling over the Continental Divide. As we entered the clouds, diffuse green light and vine-covered trees contrasted with the rust-red soil exposed in the roadcuts. We turned off Highway 2 at Empalme and headed west on a narrow, winding, and very well-maintained road into Los Santos, the heart of Costa Rican coffee country.
It was pouring when we arrived in the small town of Santa María de Dota. The picturesque town filled the bottom of a steep-walled valley, with coffee plantations covering the lower slopes and forest on the steep ridges above. A few landslide scars ran down the valley walls and a pair of enormous red and white metal microwave towers rose high above the valley floor. The modern, warehouse-sized coffee cooperative on the main road sat a couple of blocks from the traditional town square. Promptly at 6 P.M., thunder joined the rain to herald the tropical sunset.
MICROBIAL BREW
The next morning, the sun shone brightly as we set off to visit Felicia Echeverría at her small farm in San Pablo, a few miles west. Along the way, roadcuts exposed gray volcanic rock fading upward into orangeish weathered rock and clayey subsoil with little topsoil and no organic matter on top. Everywhere I looked, red dirt peeked out from bare exposed ground. Even the river was flowing orange-brown after the previous night’s rain.
Across the valley, rows of coffee bushes inscribed dotted contours across the hillsides, each bush pruned to the height of a person to keep harvesting simple. Donnelly says the coffee farmers complain that yields are going down, even though they’re applying more fertilizer than ever before. He thinks they know they are on an agrochemical treadmill. “Everybody sees the writing on the wall. All the growers know it won’t be viable for much longer.”
I could see why after we turned right at the church in San Pablo and headed up a narrow paved road that proved a struggle for our car to climb. All the roadcuts told the same story. We stopped at one so that I could photograph it and read for Donnelly the classic tale of hillside agriculture eroding off the topsoil. Clayey blocks of reddish subsoil extended right to the ground surface. There was no topsoil, no organic matter cover. I saw soil leached of available nutrients and enriched in the insoluble iron and aluminum oxides left behind as warm rainwater percolated through the ground. No wonder these farmers need a lot of agrochemicals. Their soil is shot.
A third of the way up the ridge, we left the paved road, bouncing along a dirt track past small farms, patches of forest, and more coffee fields. Donnelly looked for Echeverría’s place while trying to avoid getting stuck in the slick red gumbo of wet strips of the road. Still thinking her place must be just ahead, we reached the ridge crest, where a patch of native forest stood preserved. On the outside of a bend, the two-foot-tall roadcut exposed the forest soil: six inches to a foot of dark organic-rich topsoil on top of red subsoil. Finally, here was fertile soil much like what this land had when first cleared for farming—loose, crumbly black-brown silt capped with organic matter. Right below this fragile layer was the hard blocky subsoil now exposed at the surface on farms all around the valley. Less than a century of coffee cultivation had destroyed the soil and the region’s native fertility.
Realizing that we must have already passed Echeverría’s place, we retreated back down the mountain. We eventually found her waving us down from a tidy fenced compound as we approached from the wrong direction. She greeted Donnelly like the old friend he is and invited us into her small one-room wooden house. One side had a blue-and-yellow-tiled kitchen with a large metal worktable where she makes the salad dressings she sells for a living. Her farm grows all the herbs this venture uses—and most of her food.
Echeverría was in her fifties, thin with a curly halo of black hair. Clad in jeans, muck boots, and a white shirt, she was a bit taller than Donnelly. She had a light step and a warm intelligence, and something about her reminded me of the Frida Kahlo we know from the artist’s self-portraits.
From 1999 to 2006, Echeverría led the organic program at the Ministry of Agriculture. She bought her own 4-acre farm after a divorce and moved there in 2010, once she’d saved up enough to build the house. She not only wanted to restore her farm’s degraded soil, she wanted to show farmers that a single woman in her fifties could do it—and convince them that they could too.
The first thing she wanted to show us was her dry composting toilet, which uses a single cup of water per flush. She’d seen too many rivers and lakes in Central America that smell like human waste and thinks that people need to do their business differently. With no tank, her toilet uses just enough water to lubricate material going down. A squirt from a short hose hanging on the wall can move any stubborn stuff along. Rainwater collected off the roof supplies the toilet, which drains to a tank full of wood chips where solid material collects. She turns it once a week, periodically adds more wood chips, and empties it just once a year.
She then mixes it all with kitchen scraps and lets it compost for a couple of months before applying it back to her banana trees or flowers. “I don’t think of this as a fertilization system. It’s a way to reuse your waste.” Her kitchen water and toilet water pass through an underground filter of rocks and soil before flowing out onto the slope to water her flower garden—but not her herbs, she’s quick to point out. She showed us her latest batch of finished compost. There was no odor, and it looked like rich soil.
Walking through her herb garden, I couldn’t help but notice hummingbirds big and small darting about. The terraced hillside was well stocked with dill, lemongrass, rosemary, lavender, and a host of herbs I didn’t recognize.
The second thing Echeverría wanted to show me was back in the octagonal, open-air, cement-floored structure in front of her house. There in large blue and white containers, she makes a bokashi leachate using MM (EM-may EM-may), shorthand for microorganismos de montaña (mountain microbes). This low-tech microbial inoculant employs a sourdough-like starter to brew up a biofertilizer rich in mycorrhyzal fungi. To get it going, Echeverría collects a bag full of organic matter (humus) from the forest floor, making sure that it contains white fungal hyphae. Next, she removes all the big leaves and mixes it up with rice bran and molasses. She then covers it with a plastic bag in 60-liter, screw-top containers and lets it ferment for a month and a half.
She carefully unscrewed the top of a container and I peered inside. A faint, sweetly pungent odor drifted up to meet my nose. The resulting product boosts soil fertility and plant growth and health—if made properly.
This fine, granular stuff also serves as a starter for aerobic microbial tea. To make this, Echeverría submerges a bag of the solid material in water mixed with molasses. After steeping for two weeks, this turns into a fungus-rich brew of organisms cultivated from forest soil. She applies the fermented solids to seedlings and her planting beds, and sprays the MM-rich solution on her corn, beans, potatoes, yucca, taro, garlic, oats, and other crops to inoculate them with beneficial microbes.
“We use this all over Latin America because it is cheap and it works,” she told us. But she quickly added that you have to be careful to recognize a bad batch of MM, in which the wrong fungus has grown and, if used, could harm plants. To emphasize her point, she unscrewed a container holding a batch that had gone bad. I was immediately accosted by a sulfurous stench rising from the anaerobic muck inside. If that’s the test, it seems pretty easy to tell when it’s gone off. Still, it’s hard to standardize a biochemical process that starts with a shovelful of forest soil. And because it’s not reliably repeatable, it invites skepticism among scientists despite farmers’ experience that it works—most of the time, anyway.
Nonetheless, Echeverría showed me a Ministry of Agriculture booklet that spells out recipes for using this approach to make manure without a cow. Not all farmers have access to livestock, but they all have access to soil. In her experience, the recipe for MM is easy, cheap, and enhances soil fertility. Just fill a large container, such as a 55-gallon drum, with six parts forest soil (humus) to four parts rice bran and a gallon of molasses, mix it all up, seal it, and let it ferment anaerobically. When brewed correctly, this makes a good fertilizer that can also serve as a supplemental feed to introduce beneficial microbiota into chickens and cows.
Echeverría also makes fermented compost that includes about 10 percent biochar. This practice of making bokashi to cultivate beneficial microbial life was introduced to Costa Rica in the 1990s by a disciple of Dr. Teruo Higa, who modified a traditional Japanese practice he’d learned from his grandmother. It caught on enough with Costa Rican farmers that the Ministry of Agriculture published a recipe for making it. It looks something like this: mix chicken manure, sugar-cane waste, liquid or solid MM, charcoal (or ash), molasses, rock dust, and old bokashi. The agency particularly recommends it for spurring seedling growth.
I was also intrigued by Echeverría’s recipe for an all-purpose pesticide, homemade from ingredients that, except for the MM, would double as tasty additions to a good lunch: garlic, hot chili, onions, ginger, molasses, vinegar, alcohol, and water. After fermenting for fifteen days, the mixture can be diluted and sprayed to control insects, nematodes, fungus, and other pests. It sounds like it would also make a fine hot sauce.
Echeverría describes herself as a biointensive farmer, someone who tries to grow everything she needs to feed herself and her soil. “Biointensive is like biodynamic without the weird part. It’s much more normal—farmers here would not follow the voodoo stuff.” She ignores the spiritual and mystical aspects of biodynamic farming and its talk of cosmic forces in the soil and simply plants according to what she likes to eat and what makes good compost.
We marched a few hundred meters up the dirt road above her house to her fields, past the neighbor’s highly fertilized conventional coffee plants rising out of crusty red dirt. Along the way she explained the basis for her biointensive system: keep the ground covered and use mulch, mixed crops, and inoculation with MM solution. She doesn’t use chemical fertilizers or pesticides. To prepare a new planting bed, she digs down two feet to break up her blocky soil. Then after planting, she doesn’t disturb the ground. This sounds a lot like the principles of conservation agriculture used by Beck, Boa, and Brown—with the addition of microbial inoculation to kick-start an invisible herd of microscopic livestock.
Echeverría said that her original soil was so hard she had to use a pickaxe to break it up and so clayey she used it to make pottery. Determined to show me what she was up against, she grabbed a pitchfork, walked over to an unplanted edge of her field, jammed the business end into the ground, and jumped up on its flat bar. It went nowhere. She jumped up and down on it some more. It still went nowhere. No wonder the prior owner abandoned the farm.
When she bought the place, it was covered in wild blackberries, a few trees rising through the brambles. Now she has twenty-two planting beds nestled between fruit trees. She also planted nitrogen-fixing trees and others that produce nitrogen-rich leaves ideal for composting.
Initially, she had a hard time making a go of it. In her first year, she burned up all her savings, ran up $2,000 in credit card debt, and still wasn’t producing enough food to feed herself, let alone harvest marketable crops. When she got her soil test back, she found her unproductive soil was particularly low in calcium and boron. A soil-scientist friend interested in biointensive farming recommended using rock dust, micronutrient solutions, pig manure, and extra compost.
Within a few months, she saw major improvement in her soil. Her planting beds produced seven-foot-tall corn, a far cry from her first sickly crop of stunted purple ears. It was all a matter of applying the right combination of rock minerals, organic matter, and, she thinks, microbes to access the nutrients in minerals and organic matter. And getting something to grow in the first place helped spark the process. When she pulled out her first stunted carrots, a halo of surrounding soil was black, a fertile ring slowly growing out into the red soil.
We bent down and easily dug our hands into the now loose, brownish soil of her planting beds. She’s still amazed by the changes in her soil and the healthy crops of oregano, rosemary, and mustard seeds that support her salad-dressing business.
Pleased that she could bring bad soil back into production so fast, she began spreading compost and applying MM to her whole farm. In addition to her corn, tomatoes, and beans, she’s growing guava, blackberries, peaches, avocados, lemons, and oranges. When I noted that she’s basically planted a supermarket, she responded, “Yes, that’s the whole idea.”
She thinks that her approach can bring a farm back to producing good crops within two or three years. She wants to show other farmers in the region how to make a living out of returning life to the land, and how quickly land can be brought back to productivity—and prosperity. As the rain started back up later that afternoon, all three of us piled into the car and drove down the mountain to meet a coffee grower who was trying to rebuild his soil too.
On the way, Echeverría told us that coffee yields have dropped over the last fifteen years. It used to be controversial crazy talk to say harvests were down because agrochemical farming degraded the soil. But now, she says, it’s common knowledge among farmers.
We were a bit early to meet her friend, so Echeverría took us to see Gabriel Umaña, the local agent for the Ministry of Agriculture. We ducked out of the rain into his single-story blue office. Umaña looked like an engineer in his button-down shirt, thick dark-rim glasses, and gray slacks. He was talking with a pair of coffee farmers who were seeking advice about how to test their soil. Even my limited Spanish was enough to catch that one of the farmers uses less than half the chemical fertilizer he used to. The other said that he’d cut his use by almost three-quarters. They both wanted advice on how to further improve their soil and cut chemical inputs (and costs).
After Echeverría conducted a round of introductions, Umaña told us that the pair is not unusual. A lot of small farms have started making big changes—planting more shade trees, composting, and trying to use less pesticide and herbicide. Some were applying more organic matter to their land, and even the town’s coffee cooperative was using their coffee pulp to make compost.27 Interest in such changes had started a decade ago, when the Ministry of Health cracked down on dumping coffee pulp into rivers. Now the cooperative sells composted pulp back to members at good (cheap) prices to apply on their fields.
He’s seen farmers starting to warm to the challenge of increasing soil organic matter and cultivating soil life. Increasingly, they see how soils with less organic matter and less microbial activity produce bad-quality coffee and plants more vulnerable to disease. Healthy, fertile soils produce better coffee with less expense for chemicals and lower risk of disease.
Umaña encourages farmers to think of roots as the heart of their crops. And the roots, he tells them, need the good microbes to deliver minerals and cycle organic matter. He tells them that farmers who apply too much herbicide and fertilizer kill off the beneficial microbes and create new problems for themselves. Although he finds that most farmers know little about microbial life, he thinks it is when a farmer begins to understand the relationship between minerals, compost, and microbes that they can really start to manage and improve soil health. So he’s trying to teach them.
